Effect of rosemary extract and vitamin e on lipid peroxidation and the quality during chilling and frozen storage of fried Nile tilapia fillets (Oreochromis niloticus)

Research Article | DOI: https://doi.org/10.31579/2693-4779/029

Effect of rosemary extract and vitamin e on lipid peroxidation and the quality during chilling and frozen storage of fried Nile tilapia fillets (Oreochromis niloticus)

  • Ibrahim F. Mohamed ID 1
  • Mohamed F. Madi ID 1

*Corresponding Author: Ibrahim F. Mohamed, Faculty of Public Health, Benghazi University, Libya.

Citation: Ibrahim F. M and M F. Madi. (2021) Effect of rosemary extract and vitamin e on lipid peroxidation and the quality during chilling and frozen storage of fried nile tilapia fillets. Clinical Research and Clinical Trials. 3(5); DOI: 10.31579/2693-4779/029

Copyright: © This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: 24 February 2021 | Accepted: 20 March 2021 | Published: 31 May 2021

Keywords: vitamin e; lipid peroxidation; Rosemary extract

Abstract

Antioxidants are added to fresh and processed meat to prevent lipid oxidation, retard development of off-flavors, and improve color stability. In the food industry, they can be divided into natural and synthetic antioxidants. Synthetic antioxidants have been confirmed for their toxicological and carcinogenic effects. Thus, the food industry now chooses natural products over synthetic ones.

This study was carried out to investigate the effect of Rosemary extract (R.E.) and vitamin E on the quality of fried fillets of Nile tilapia (Oreochromis niloticus) during chilling and frozen storage. Fillets of Nile tilapia were treated with (R.E.)  0.1%, 0.2%, 0.3% and Vitamin E 0.1% then stored for 5,10 and 15 days at 4±1°C and for three months at -18±2°C. Then chemical tests including Peroxide value (PV), Thio-barbituric acid (TBA), Tri-methylamine-nitrogen (TMA-N) and Total volatile base-nitrogen (TVB-N) were done to evaluate the preservative effect of (R.E.) and vitamin E during storage. The TBA and PV increased in all treatments due to lipid peroxidation. Results showed that TMA-N,TVB-N, value of (R.E.) and vitamin E treated samples were significantly lower than those of the control samples (P<0.05). Results of our investigation revealed that R.E. retarded oxidative changes in chilling and frozen fried fillets of Nile tilapia whereas R.E. 0.1%, 0.2% and vitamin E 0.1% were not as effective as R.E. 0.3%  on oxidative stability. Best oxidation inhabitation results on chilling and frozen fried fillets of Nile tilapia was obtained when employing of R.E. The obtained results also showed that there was a significant (p<0.05) enhancement in sensory quality attributes of fried fillets of Nile tilapia; samples treated with R.E. and vitamin E

Conclusion: The tested R.E. had a high effectiveness as antioxidative and antimicrobial should be utilized for extending the shelf-life through retarded the spoilage and enhancing quality attributes of fried fillets of Nile tilapia during chilling and frozen storage.

Introduction

The quality attributes of meat products deteriorate, because the lipid oxidation during processing and storage. Lipid peroxidation is responsible for development of primary and secondary peroxidation products, reduction in nutritional quality, as well as changes in flavor (Maqsood and Benjakul 2011a), that can be precipitated health hazards and economic losses in terms of inferior product quality (Naveena et al., 2008) (Gema, et al., 2018). Lipid peroxidation is a rather complex process whereby unsaturated fatty acid fraction of membrane phospholipids are oxidized, and hydroperoxides are formed which are further susceptible to oxidation or decomposition to secondary peroxidation products, as short-chain aldehydes, ketones, and other oxidized compounds which may adversely affect the overall quality and acceptability of meat products and fish meat. Antioxidants are compounds that are capable of donating hydrogen (H·) radicals (Masuda and others 2001), (Jun .et al., 2019) for pairing with available free radicals to prevent the propagation reaction stage during the oxidation process. This effectively minimizes rancidity, retards lipid peroxidation, without any damage to the sensory or nutritional properties, resulting in maintaining quality and shelf-life of fish and meat products. Also, intrinsic factors are available in live muscle to prevent lipid peroxidation. These factors are often lost after slaughtering during conversion of fish muscle to meat, primary/secondary processing, handling, or storage of meat products, necessitating further supplementation with extrinsic antioxidants.

For this reason, synthetic antioxidants, such as rosemary extract, were extensively used to delay, retard, or prevent the lipid oxidation by scavenging chain-carrying peroxyl radicals or suppressing the formation of free radicals. However, because of the concern over the safety of these synthetic compounds, extensive work is being carried out to find novel and naturally occurring compounds to delay the peroxidation degradation of lipids, improve quality, and maintain the nutritional value of foods (Ciriano and others 2009, 2010)( Dimitrios et al 2007). Thus, natural antioxidants have greater application potential in the fish meat industry due to the consumers’ acceptability over the synthetic antioxidants. However, the application of plant extracts, spices, herbs, and essential oils with antioxidant effects is still distant for the major reasons of limited data about their effects in different fish meat products.

Pan-frying is a popular method of preparing fatty fish, since it is fast, convenient, and can generate typical characteristics of color, flavor, texture, and palatability, which is highly appreciated by consumers. The high temperatures generated from pan-frying may breakdown EPA and DHA through lipid oxidation. Also,studies suggest that the heat from pan-frying, not only increase the oxidation of fatty acids on the surface, but also inside fish meat. Kin et al (2019).

Lipid oxidation is one of the most important factors responsible for quality deterioration of fish during both refrigerated and frozen storage (Serdaroglu and Felekoglu, 2005). The investigated studies show that freezing is one of the best methods for long-term fish maintenance (Verma and Sriker, 1994; Vidya Sagar Reddy and Sriker, 1996 and Aubourg et al., 2005). Freezing prevents microbial spoilage and helps to reduce fat oxidation but cannot prevent it. One of the appropriate methods to access this target is using additives such as antioxidants. The use of antioxidants is emerging as an effective methodology for controlling rancidity in oils and food (Pazos et al., 2005; Rostamzad et al., 2011 and Taheri et al., 2012).  The application of synthetic and natural antioxidants to control lipid oxidation in sea foods is well established (Khan et al., 2006).

To prevent and delay the quality changes caused by lipid oxidation in foods and seafood, various synthetic antioxidants have been used (Benjakul et al. 2005). However, with growing concerns regarding the safety of synthetic antioxidants, natural antioxidants have been suggested as safe alternative to synthetic antioxidants to retard oxidative processes and to improve the keeping quality of fish. This ability is due to their potential as free radical scavengers which may terminate radical chain reactions and display antibacterial effects against bacterial pathogens (Singh et al., 2005) and (Sarabi et al., 2017). The bacteriostatic effects of spices may occur through two mechanisms: the delay and partial inhibition of DNA and proteins synthesis (Feldberg et al., 1988). Spices and herbs have been added to food since ancient times, not only as flavoring agents, but also as folk medicine and food preservatives (Nakatani, 1994). Furthermore, certain spices and herbs were used as green materials, plant extracts; essential oils (EOs) and powders for prolong the storage life of foods by preventing rancidity through their antioxidants activity or through bacteriostatic or bactericidal activity, also to food-borne pathogenic bacteria (Shelef et al., 1980). Essential oils (EOs) contain a mixture of compounds, which includes terpenes, alcohols, acetones, phenols, acids, aldehydes, and esters and mainly used as food flavorings or functional components in pharmaceuticals (Corbo et al., 2009)

Among natural antioxidants, rosemary (Rosemarinus officinalis) has been used successfully as an antioxidant in different kinds of fish species Sardine (Sardine pilchardus) by Serdaroglu and Felekoglu (2005),Escolar (Lipidocybium flavobrunium) by (Sarabi et al., 2017) and Tilapia (Oreochromis niloticus) by Ibrahim and EL- Sherif (2008).

Rosemary (Rosmarinus officinalis) oil is well known as a common spice which extensively used in the food industry. Antioxidant efficiency of rosemary extract or oil is due to high content of phenolic compounds; monoterpenes (eteric olis), diterpene phenols (carnosic acid, carnosol, rosmanol, epirosmanol, isorosmanol, methylcarnosate), phenolic acids (rosmarinic acid), flavonols and triterpene acids (ursolic acid, oleanolic acid, butilinic acid) which break free radical chain reactions by hydrogen atom donation (Rıznar et al., 2006). The anti-oxidative effect of rosemary is based on its phenolic diterpenes, creosol and carnosinic acid as well as rosmanol, epirosmanol and iso-rosmanol (Inatani et al., 1983; Schwarz et al., 1992).

Many studies were carried out to prove the effect of combination of refrigeration and essential oils on extending the shelf-life of fish and fish products (Zakipour and Divband, 2012).

Therefore, this study was carried out to investigate the effect of Rosemary extract and vitamin E on improve the quality and extending the shelf-life of fried Nile tilapia (Oreochromis niloticus) during chilling storage at 4±1ºC for 15 days and fillets of frozen storage up to 3 months by determination of physico-chemical, microbial and sensory quality criteria so, shelf-life periodically during storage period.

MATERIALS AND METHODS Samples preparation

Nile tilapia (Oreochromis niloticus) was used in this study. An initial batch was directly obtained from special farm in Benghazi. The fish samples were transferred to the laboratory of department of food science and technology (Public Health - Benghazi University). All of the fish (32.200 kg.) were immediately washed with tap water. The head, scales and all fins of the fish were removed using a sharp knife. Therefore, the fish were washed again and soaked in tap water for one hour and dressed in a fillets style weighting of each fillet was approximately 90±10 g, then fillets were divided into 5 groups. Samples of the first group were left untreated (control) and dipped in edible coating solution (without any antioxidant) and packaged in polyethylene bags. Coating agents including (onion powder, starch, gluten, salt, garlic powder, isolated soy protein, sodium caseinate, lime juice, blend spice, white pepper, red pepper, sodium ascorbate and whole egg) were obtained from local market, Fillets belonging to the second, third and fourth groups were dipped into edible coating solutions containing 0.1%, 0.2% and 0.3% of (R.E.) respectively, whereas the fifth groups were dipped in edible coating solution containing 0.1% vitamin E.

All tilapia fillets groups were left at room temperature and then pan-fried using an electrical fryer pan in frying oil (without antioxidant) heated at 170°C for 4 minute, then drained in a basket to remove excess oil and then packed and chilling storage at 4±1ºC for 15 days and frozen storage up to 3 months at -18°C to evaluate the effects of antioxidant of RE and vitamin E during the storage. Samples were randomly drawn for analysis at every 5, 10 and 15 days through chilling storage and at every one month periods through frozen period. For all five groups of tilapia fillets analyses were carried out after the chilling and freezing process. For each type of fillets, five different batches (n=5) were considered and analyzed separately in order to achieve the statistical analysis.

Plant Extract

Rosemary (Rosemarinus officinalis L.) was dried, extracted by ethanol (80%) in the laboratory of department of food science and technology (Public Health - Benghazi University), and then extract was concentrated by rotary evaporation and freeze drying system.

Lipid oxidation measurements

Peroxide value (PV) was determined in the lipid extract according to the method described by AOAC (2000). Results are expressed as milliequivalents oxygen per kg lipid (meq O2/kg lipid). Thio-barbituric acid (TBA) was determined calorimetrically by the Porkony and Dieffenbacher method as described by Kirk and Sawyer (1991). Results are expressed as mg malonaldehyde/kg (mg MAL/kg) fish muscle. on base total oxidation, including primary and secondary oxidation products. Which is a combination of PV and TBA (Totox value =2PV+TBA).

Volatile amine formation

Total volatile base-nitrogen (TVB-N) values were measured by the direct distillation method according to Goudlas and Kantians (2005). The results are expressed as mg TVB/N 100 g-1 muscle. Tri-methylamine-nitrogen (TMA-N) values were determined by means of the picrate method, as previously describe by (Aubourg et al., 2007). This involves the preparation of a 5% (w/v) trichloroacetic acid extract of fish muscle. The results are expressed as mg TMA/N 100 g-1 muscle.

Organoleptical evaluation

Samples were organoleptically evaluated for colour, taste, flavour and overall acceptability. A group of 10 staff members of department of food science and technology (Public Health - Benghazi University), as judges checked the organoleptic properties of the samples and grades ranged from zero to 10 (Teeny and Miyauchi, 1972) as mentioned in Table (1).

Table 1. Description of organoleptic properties scores.

Statistical analysis

Three replications of each trial were performed. Moisture, protein, fat, ash, total volatile bases nitrogen (TVBN), trimethylamine nitrogen (TMAN), thiobarbituric acid (TBA), peroxide value (PV), and sensory data were analyzed using ANOVA and means were separated by Duncan' test (1955) at a probability level of P<0.05 (SAS, 2000).

RESULTS AND DISCUSSION

Chemical composition of raw tilapia fillets and treated fried fillets of Nile tilapia:

 Proximate composition of raw tilapia fillets, untreated and treated fried fillets with vitamin E and Rosemary extract during storage. Mean values for the proximate chemical composition of fresh raw tilapia fillets and storage coated fried fillets untreated and treated are given in Table 2. For raw tilapia fillets; the moisture, crude protein, fat, ash and carbohydrates contents were 77.33, 84.47, 8.00, 5.99 and 1.54%, respectively. Meanwhile, the corresponding values in fried fillets of tilapia treated with Rosemary extract 0.3% and Vitamin E 0.1% were 61.50- 62.92, 82.31-83.57, 9.44-9.15, 5.34-5.71and 2.91- 1.57% (on dry weight basis), respectively. From these results, it could be observed that due to frying of tilapia fillets, the moisture content was significantly reduced (P<0.05), while fat was significantly increased (P<0.05). Frying increased fat content, possibly as a result of both moisture content losses and absorption of some frying sun flower oil inside the tissues. It is clear from the present results that parameters chemical composition in frying of fillets of tilapia were not affected by inclusion of the plant essential oils as there were no significant different (p<0.05) between their means and those of control. These results are nearly accordance with obtained by Elagba et al. (2010).

It could be observed that chilling and frozen storage of fried fillets of tilapia resulted in significant changes (p>0.05) of gross chemical composition compared with the fried fillets of tilapia at zero time. In general, by storage at chilling at 4±1°C and freezing at –18±2°C, the moisture, protein and ash were slowly reduced. It might be assumed that with drip separated during thawing of freezing samples, some losses of moisture, protein and ash were occurred, as reported by Wen-Hsin and Lillard (1998); Puwastien et al. (1999); Santerre et al. (2000), Musaiger (2008); Erkan et al. (2010) and Ansorena et al. (2010).

Table2. Proximate composition of fried fillets of tilapia that were pretreated by Vitamin E and Rosemary extract (R.E.) on dry weight basis.a-bcMeans within a raw with the different superscript are significantly different (p<0.05).Values are expressed as Mean ± SE.

Changes in peroxide value (PV) and thiobarbituric acid (TBA)

Lipid oxidation development was measured according to the PV Changes in PV values of control and treatments RE (0.1%, 0.2%, 0.3%) and Vitamin E (0.1%) during chilling storage at 4±1°C for 15 days and frozen storage at -18°C for 3 months are shown in (Table 3). Initial PV values of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 5.81, 5.42, 5.37, 5.29 and 5.52meq O2/ kg and increased to 11.98, 8.94, 6. 87, 5.63 and 9.96, respectively after chilling storage period and increased to 11.81, 8.71, 7.63, 5.54 and 9.84 respectively after freezing storage period.

All samples of fried fillets of tilapia showed an increase in PV value in when the chilling and frozen storage increased (P<0.05). Control samples showed highest formation rate of peroxide value in compare with all the treatments and after that, the highest rate was found is samples contained 0.1% Vitamin E during storage period. Samples contained 0.3% of RE showed the lowest rate of peroxide formation.

Table 3:Changes of Peroxide values (meq O2/kg Oil) during Cold and frozen storage of fried tilapia fillets that pretreated by Rosemary extract and Vitamin E for 15 days at 4±1°C and for three month at -18±2°C.(On wet weight basis). a-eMeans within a raw with the different superscript are significantly different (p<0.05). Values are expressed as Mean ± SE.

As shown in (Table 4). Initial TBA values of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 0.34, 0.27, 0.23, 0.20 and 0.32meq O2/ kg and increased to 1.31,  0.95, 0.86, 0.69 and 1.17 respectively after chilling storage period and increased to 1.2,  0.82, 0.73, 0.62 and 1.05 respectively after freezing storage period.

There were increased TBA value in fried tilapia fillets when the chilling and frozen storage period increased (P<0.05). The TBA values of RE treatments were significantly lower than the control and Vitamin E after 5 days of chilling storage and one month of frozen storage (p<0.05).  After storage more differences were found in TBA values between the control and RE treatments. The increment in TBA and PV during storage could be resulted from lipid oxidation; these results are in harmony with those obtained by Darweash (1996); Raju et al. (1999) and Aro et al. (2000).

Table 4: Changes of Thio-barbituric acid (mg mal/kg fish muscle) during Cold and frozen storage of fried fillets of tilapia that were pretreated by Vitamin E and Rosemary extract (R.E.)for 15 days at 4±1°C and for three month at -18±2°C.(On wet weight basis). a-cMeans within a raw with the different superscript are significantly different (p<0.05). Values are expressed as Mean ± SE.

The peroxide value of a sample indicates the concentrations of peroxides and hydro-peroxides that are produced during the early stages of lipid oxidation. The peroxide values are monitored for a sample and when it sharply increases, it indicates the end of the shelf life for that sample. The main use of a peroxide value is to determine the quality of oil sample (Kaya et al., 1993). Increase of PV in control samples in contrast with all treatments showed development of off-flavor is one of the major effects of lipid oxidation (Fagan et al., 2003 and Sahari et al., 2009) and at the further stage of lipid peroxidation; changes in color and nutritional value are observed (Sahari et al., 2009). In control samples PV<20 meq O2/kg were obtained at the end of the period. However, all treatments (RE 0.1%, 0.2%, 0.3% and Vitamin E 0.1%) showed a progressive but slow increase (P<0.05) with storage period. The lowest PV was observed for fried fillets of tilapia treated with RE 0.3%. According to the results, it is concluded that RE treatments had significant effect on delaying lipid oxidation. Similar to our findings Serdaroglu and Felekoglu (2005) reported the anti-oxidative effect of rosemary extract for sardine (Sardina pilchardus). Increase in PV values of fried and chill-reheated samples also reported by Nikoo et al. (2010) which indicated that lipid oxidation took place during frying and reheating process. As reported by Al- Saghir et al. (2004) in addition of heat treatment, the kind of cooking oil also can alter the peroxide value. Similar to our results, Nessrien Yasin and Abou-Taleb (2007) reported that PV value increased in semi fried mullet fillets of tilapia during cold storage. At the end of storage period, lowest TBA value was recorded as 5.54 mg MAL/ kg oil for the RE 0.3% treatment. TBA values indicated that control samples had more rancid than samples treated with RE, throughout the storage period.

Treatment with containing of synthesis antioxidant (Vitamin E), showed lower antioxidant effect in comparison with all of the concentrations of rosemary. Similar results were found for the same process by Nessrien Yassin and Abotaleb (2007) that they studied on antioxidant effect of thyme and marjoram on semi fried mullet fish fillet in 4°C storage. These results are in agreement with those reported by Ibrahim and EL-Sherif (2008).

Totally, the results showed that usage of RE and Vitamin E had positive influence on delaying lipid oxidation and increasing shelf-life of tilapia fillets (P<0.05). TBA values indicated that control samples and samples with added Vitamin E were more rancid than samples treated with RE throughout the storage time. Frying and chilled storage followed by reheating also increased the TBA value, indicating that the secondary products of oxidation increased during the procedure.

Although the lipid oxidation occurred during frying or subsequent storage and reheating, TBA value were lower than acceptability level for human consumption reported by Nikoo et al. (2010). The level of 7-8 mg MAL/kg oil is the limit of acceptability of TBA. Results showed that RE 0.3% was the most effective antioxidant. Similar results were reported by Serdaroglu and Felekoglu (2005) on Sardine mince and Nikoo et al. (2010) on Kutum.

Changes in total volatile bases nitrogen (TVBN)

Production of total volatile bases nitrogen (TVBN) and increment in trimethylamine nitrogen (TMAN) in fish muscles during storage could be used as indicator of bacterial activity. TVBN and TMAN are considered a valuable tool in the evaluation of fish quality during storage because it’s rapid accumulation in muscles under storage conditions. Increasing mean values of TVB-N were observed with longer storage periods (Table 5). Initial (TVBN) values of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 13.77, 13.43, 13. 28, 13.1and 13.61 meq O2/ kg and increased to 14.21, 13.56, 13.20, 13.12 and 13.98, respectively after chilling storage period and increased to 14.1, 13.44, 13.10, 12.91 and 13.88 respectively after freezing storage period.

All samples showed an increased TVB-N value in coated fried fillets of tilapia when the  chilling and frozen storage period increased (P<0.05), there were Significant differences between control and all treatments during storage period (P<0.05) whereas significant difference was recorded between treatment groups (RE 0.1%, 0.2%, 0.3% and Vitamin E 0.1%) during storage period (P<0.05), at the end of storage time the lowest TVB-N level was found in samples treated with RE 0.3%. In general, as the concentration of RE increased, the TVB-N value was decreased.

Table5. Changes of TVB-N values (mg/100g sample) during Cold and frozen storage of coated fried fillets of  tilapia that were pretreated by Vitamin E and Rosemary extract (R.E.) for 15 days at 4±1°C and for three month at -18±2°C.(On wet weight basis).a-bcMeans within a raw with the different superscript are significantly different (p<0.05). Values are expressed as Mean ± SE.

The TVB-N content quantifies a wide range of basic volatile compounds (ammonia, methylamine, di-methylamine, tri-methylamine, and etc) that should be produced as a result of microbiological activity during the chilling storage or arise from the thermal breakdown of endogenous compounds during cooking (Rodrıguez et al., 2008). In comparison with the values reported by (Nessrien Yassin and Abotaleb, 2007), formation of TVB-N was slightly higher for all treatments from the beginning until the end of period of storage. Increase in TVB-N during storage can be due to increase of released ammonia from amination of adenosine monophosphate or histamine (Sahari et al., 2009).

In this study, increase in TVB-N level may be a result of ammonia releasing and other volatile amines from muscular damaged tissue. The increment in TVB-N content during storage period may be due to bacterial activity. However, the breakdown occurred in fillet proteins in rosemary extract was of low rate and might be due to antimicrobial agent of rosemary extract (Ibrahim and EL-Sherif, 2008). The level of TVB-N in freshly caught fish is generally between 5 and 20 mg N/100g muscle. However, the levels of 30-35 mg N/100g muscle are considered the limit of acceptability for ice-stored cold water fish (Zarei et al., 2011). In our study TVB-N value for all treatment groups did not exceed 15 mg/100g sample.

Changes in trimethylamine nitrogen (TMAN)

Amine formation in coated fried fillets of tilapia during storage period was also measured by the TMAN content (Table 6). Initial (TMA-N)  values of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 2.35, 1.71, 1.49, 1.38 and 2.10 meq O2/ kg and increased to 2.79, 2.07, 1.87, 1.76 and 2.50, respectively after chilling storage period and increased to 2.68, 1.96, 1,78, 1.65 and 2.39 respectively after freezing storage period.

All samples showed an increased TMA-N value in fried fillets of tilapia when the storage period increased (P<0.05). There were Significant differences between control and all treatments in storage period (P<0.05) whereas significant difference was recorded between treatment groups (RE 0.1%, 0.2%, 0.3% and VitaminE  0.1%) during storage period (P<0.05). At the end of storage time the lowest TMA-N level was found in samples treated with RE 0.3%.

Concerning TMA-N its content slightly increased may be due the conversion of TMAO oxide to TMA (Ibrahim and El-Sherif, 2008). TMA-N is often used as an index in assessing the shelf-life and keeping quality of sea food products because rapidly accumulates in the muscle under cold and frozen conditions. The TMA-N production in fish tissue during cold storage could be used as an indicator of bacterial activity and it is an accepted deterioration measure. The pungent odor of spoiled fish has been often related to TMA-N tissue levels, also with the number of spoiling organisms present in many fish species and the rejection limits is usually from 5 to 10 mg TMA/N 100 g-1 muscle (Zarei et al., 2011). Our results were far below the limit of acceptability of 10-15 mg TMA/N 100 g-1 (Selmi and Sadok, 2008) in all treatments during cold and frozen storage period. TMA formation in the actual fried samples can be explained by means of two different pathways: (1) As a result of TMAO bacterial catalysis breakdown during the chilled storage, and (2) TMA can be produced from TMAO by thermal breakdown during the frying process (Rodriguez et al., 2008). From the TMA-N results, the samples treated with 0.3% RE have higher effect on the bacterial growth in fish samples during cold and frozen storage than other treatments. The application of natural antioxidant (rosemary) in coating layer of fillets of tilapia stored under cold conditions resulted in a decreased microbial population compared to control samples as proved by several other studies on the essential oils of natural antioxidants (Nessrie Yasin and Abou-Taleb, 2007). Similar to our results, Ibrahim and El-Sherif (2008) reported that TMA-N levels of rosemary extract added to fillets of tilapia were significantly lower than control samples after 4 months storage at -18°C.

Table 6: Changes of TMA-N values (mg/100g sample) during chilling and frozen storage fried fillets of tilapia that were pretreated by Vitamin E and Rosemary extract (R.E.) for 15 days at 5±1°C and for three month at -18±2°C. (On wet weight basis).a-bMeans within a raw with the different superscript are significantly different (p<0.05). Vitamin E alues are expressed as Mean ± SE.

Organoleptic evaluation

Organoleptic evaluation scores of colour, taste, flavour and overall acceptability estimated during chilling and frozen storage fried fillets of tilapia that were pretreated by Vitamin E and Rosemary extract for 15 days at 4±1°C and for 3 month at -18±2°C are presented in Table 7.

Initial colour scores of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 9.3,9.2,9.1,9.0, and8.9 respectively and decreased to 8.4, 8.0, 8.3, 8.5  and 8.0 respectively  after chilling storage period and decreased to 8.6, 8.4,8.5,8.6  and 8.31 respectively after freezing storage period.

Table 7: Colour and taste scores during chilling and frozen storage fried fillets of tilapia that were pretreated by Vitamin E and Rosemary extract (R.E.) for 15 days at 4±1°C and for three month at -18±2°C. E= Excellent.;V.G. = Very good.;G= Good.;F.G. = fairly good.

Initial taste scores of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 9.3,9.3,9.2,9.1, and8.9 respectively and decreased to 8.5, 8.4, 8.3, 8.5 and 8.0 espectively  after chilling storage period and decreased to 8.7, 8.5,8.0,8.5  and 8.3 respectively after freezing storage period.

Initial flavor  scores of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 9.5,9.4,9.2,9.3, and9.1 respectively and decreased to 8.5, 8.5, 8.3, 8.5 and 8.0 espectively  after chilling storage period and decreased to 8.7, 8.5,8.0,8.6  and 8.3 respectively after freezing storage period.

Initial Overall acceptability scores of control, (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% treatments were found 9.0, 9.1, 9.0, 9.1, and 8.8 respectively and decreased to 8.4, 8.0, 8.2, 8.3 and 79.0 respectively  after chilling storage period and decreased to 8.6, 8.4, 8.3, 8.5  and 8.2 respectively after freezing storage period.

Samples after frying directly showed the highest scores for colour, taste, flavour, and overall acceptability, respectively, compared with the samples of fillets of tilapia fried after chilling for 15 days at 4±1°C and frozen storage period for three months at –18±2°C respectively. The scores of colour, taste, flavour and overall acceptability showed a significant decreases (P<0.05) after storage periods.

Therefore, it could be concluded that, the gradual decrease in colour, taste, flavour and overall acceptability scores throughout the storage period at different temperatures, could be attributed to the protein denaturation, hydrolysis and fat oxidation, which are the major factors of changes in organoleptic properties during storage periods. These results are in agreement with those given by Darweash (1996); Schubring (1996) and Raju et al. (1999).

From the results obtained in the present study, it may be recommended that, the best consumption of fried fillets of tilapia is after processing directly, followed by 15 days at 4±1°C and frozen storage period for three months at–18±2°C respectively.

Table8: Flavour and Overall acceptability scores  during chilling and frozen storage fried fillets of  tilapia that were pretreated by Vitamin E and Rosemary extract (R.E.)  for 15 days at 4±1°C and for three month at -18±2°C.E= Excellent.;V.G.= Very good.;G= Good.;F.G.= Fairly good.

Conclusion

As a result of a chilling and frozen storage period, a marked content increase was found in the PV, TBA, TMA-N and TVB-N value. However, a preserving effect on such parameters could be observed due to the Rosemary and Vitamin E treatment. Results of our investigation revealed that rosemary extract and Vitamin E retarded oxidative changes in coated frozen Fried fillets of tilapia whereas RE 0.1%, 0.2% and Vitamin E as not as effective as RE 0.3% on oxidative stability. The efficiency of antioxidant inhibiting lipid oxidation throughout chilling and frozen storage was in the following order: RE 0.3% > RE 0.2% > RE 0.1% >  Vitamin E > control (P<0.05).

References

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Virginia E. Koenig

Journal of Clinical Cardiology and Cardiovascular Intervention The submission and review process was adequate. However I think that the publication total value should have been enlightened in early fases. Thank you for all.

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Delcio G Silva Junior

Journal of Women Health Care and Issues By the present mail, I want to say thank to you and tour colleagues for facilitating my published article. Specially thank you for the peer review process, support from the editorial office. I appreciate positively the quality of your journal.

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Ziemlé Clément Méda

Journal of Clinical Research and Reports I would be very delighted to submit my testimonial regarding the reviewer board and the editorial office. The reviewer board were accurate and helpful regarding any modifications for my manuscript. And the editorial office were very helpful and supportive in contacting and monitoring with any update and offering help. It was my pleasure to contribute with your promising Journal and I am looking forward for more collaboration.

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Mina Sherif Soliman Georgy

We would like to thank the Journal of Thoracic Disease and Cardiothoracic Surgery because of the services they provided us for our articles. The peer-review process was done in a very excellent time manner, and the opinions of the reviewers helped us to improve our manuscript further. The editorial office had an outstanding correspondence with us and guided us in many ways. During a hard time of the pandemic that is affecting every one of us tremendously, the editorial office helped us make everything easier for publishing scientific work. Hope for a more scientific relationship with your Journal.

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Layla Shojaie

The peer-review process which consisted high quality queries on the paper. I did answer six reviewers’ questions and comments before the paper was accepted. The support from the editorial office is excellent.

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Sing-yung Wu

Journal of Neuroscience and Neurological Surgery. I had the experience of publishing a research article recently. The whole process was simple from submission to publication. The reviewers made specific and valuable recommendations and corrections that improved the quality of my publication. I strongly recommend this Journal.

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Orlando Villarreal

Dr. Katarzyna Byczkowska My testimonial covering: "The peer review process is quick and effective. The support from the editorial office is very professional and friendly. Quality of the Clinical Cardiology and Cardiovascular Interventions is scientific and publishes ground-breaking research on cardiology that is useful for other professionals in the field.

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Katarzyna Byczkowska

Thank you most sincerely, with regard to the support you have given in relation to the reviewing process and the processing of my article entitled "Large Cell Neuroendocrine Carcinoma of The Prostate Gland: A Review and Update" for publication in your esteemed Journal, Journal of Cancer Research and Cellular Therapeutics". The editorial team has been very supportive.

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Anthony Kodzo-Grey Venyo

Testimony of Journal of Clinical Otorhinolaryngology: work with your Reviews has been a educational and constructive experience. The editorial office were very helpful and supportive. It was a pleasure to contribute to your Journal.

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Pedro Marques Gomes

Dr. Bernard Terkimbi Utoo, I am happy to publish my scientific work in Journal of Women Health Care and Issues (JWHCI). The manuscript submission was seamless and peer review process was top notch. I was amazed that 4 reviewers worked on the manuscript which made it a highly technical, standard and excellent quality paper. I appreciate the format and consideration for the APC as well as the speed of publication. It is my pleasure to continue with this scientific relationship with the esteem JWHCI.

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Bernard Terkimbi Utoo

This is an acknowledgment for peer reviewers, editorial board of Journal of Clinical Research and Reports. They show a lot of consideration for us as publishers for our research article “Evaluation of the different factors associated with side effects of COVID-19 vaccination on medical students, Mutah university, Al-Karak, Jordan”, in a very professional and easy way. This journal is one of outstanding medical journal.

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Prof Sherif W Mansour

Dear Hao Jiang, to Journal of Nutrition and Food Processing We greatly appreciate the efficient, professional and rapid processing of our paper by your team. If there is anything else we should do, please do not hesitate to let us know. On behalf of my co-authors, we would like to express our great appreciation to editor and reviewers.

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Hao Jiang

As an author who has recently published in the journal "Brain and Neurological Disorders". I am delighted to provide a testimonial on the peer review process, editorial office support, and the overall quality of the journal. The peer review process at Brain and Neurological Disorders is rigorous and meticulous, ensuring that only high-quality, evidence-based research is published. The reviewers are experts in their fields, and their comments and suggestions were constructive and helped improve the quality of my manuscript. The review process was timely and efficient, with clear communication from the editorial office at each stage. The support from the editorial office was exceptional throughout the entire process. The editorial staff was responsive, professional, and always willing to help. They provided valuable guidance on formatting, structure, and ethical considerations, making the submission process seamless. Moreover, they kept me informed about the status of my manuscript and provided timely updates, which made the process less stressful. The journal Brain and Neurological Disorders is of the highest quality, with a strong focus on publishing cutting-edge research in the field of neurology. The articles published in this journal are well-researched, rigorously peer-reviewed, and written by experts in the field. The journal maintains high standards, ensuring that readers are provided with the most up-to-date and reliable information on brain and neurological disorders. In conclusion, I had a wonderful experience publishing in Brain and Neurological Disorders. The peer review process was thorough, the editorial office provided exceptional support, and the journal's quality is second to none. I would highly recommend this journal to any researcher working in the field of neurology and brain disorders.

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Dr Shiming Tang

Dear Agrippa Hilda, Journal of Neuroscience and Neurological Surgery, Editorial Coordinator, I trust this message finds you well. I want to extend my appreciation for considering my article for publication in your esteemed journal. I am pleased to provide a testimonial regarding the peer review process and the support received from your editorial office. The peer review process for my paper was carried out in a highly professional and thorough manner. The feedback and comments provided by the authors were constructive and very useful in improving the quality of the manuscript. This rigorous assessment process undoubtedly contributes to the high standards maintained by your journal.

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Raed Mualem

International Journal of Clinical Case Reports and Reviews. I strongly recommend to consider submitting your work to this high-quality journal. The support and availability of the Editorial staff is outstanding and the review process was both efficient and rigorous.

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Andreas Filippaios

Thank you very much for publishing my Research Article titled “Comparing Treatment Outcome Of Allergic Rhinitis Patients After Using Fluticasone Nasal Spray And Nasal Douching" in the Journal of Clinical Otorhinolaryngology. As Medical Professionals we are immensely benefited from study of various informative Articles and Papers published in this high quality Journal. I look forward to enriching my knowledge by regular study of the Journal and contribute my future work in the field of ENT through the Journal for use by the medical fraternity. The support from the Editorial office was excellent and very prompt. I also welcome the comments received from the readers of my Research Article.

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Dr Suramya Dhamija

Dear Erica Kelsey, Editorial Coordinator of Cancer Research and Cellular Therapeutics Our team is very satisfied with the processing of our paper by your journal. That was fast, efficient, rigorous, but without unnecessary complications. We appreciated the very short time between the submission of the paper and its publication on line on your site.

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Bruno Chauffert

I am very glad to say that the peer review process is very successful and fast and support from the Editorial Office. Therefore, I would like to continue our scientific relationship for a long time. And I especially thank you for your kindly attention towards my article. Have a good day!

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Baheci Selen

"We recently published an article entitled “Influence of beta-Cyclodextrins upon the Degradation of Carbofuran Derivatives under Alkaline Conditions" in the Journal of “Pesticides and Biofertilizers” to show that the cyclodextrins protect the carbamates increasing their half-life time in the presence of basic conditions This will be very helpful to understand carbofuran behaviour in the analytical, agro-environmental and food areas. We greatly appreciated the interaction with the editor and the editorial team; we were particularly well accompanied during the course of the revision process, since all various steps towards publication were short and without delay".

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Jesus Simal-Gandara

I would like to express my gratitude towards you process of article review and submission. I found this to be very fair and expedient. Your follow up has been excellent. I have many publications in national and international journal and your process has been one of the best so far. Keep up the great work.

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Douglas Miyazaki

We are grateful for this opportunity to provide a glowing recommendation to the Journal of Psychiatry and Psychotherapy. We found that the editorial team were very supportive, helpful, kept us abreast of timelines and over all very professional in nature. The peer review process was rigorous, efficient and constructive that really enhanced our article submission. The experience with this journal remains one of our best ever and we look forward to providing future submissions in the near future.

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Dr Griffith

I am very pleased to serve as EBM of the journal, I hope many years of my experience in stem cells can help the journal from one way or another. As we know, stem cells hold great potential for regenerative medicine, which are mostly used to promote the repair response of diseased, dysfunctional or injured tissue using stem cells or their derivatives. I think Stem Cell Research and Therapeutics International is a great platform to publish and share the understanding towards the biology and translational or clinical application of stem cells.

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Dr Tong Ming Liu

I would like to give my testimony in the support I have got by the peer review process and to support the editorial office where they were of asset to support young author like me to be encouraged to publish their work in your respected journal and globalize and share knowledge across the globe. I really give my great gratitude to your journal and the peer review including the editorial office.

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Husain Taha Radhi

I am delighted to publish our manuscript entitled "A Perspective on Cocaine Induced Stroke - Its Mechanisms and Management" in the Journal of Neuroscience and Neurological Surgery. The peer review process, support from the editorial office, and quality of the journal are excellent. The manuscripts published are of high quality and of excellent scientific value. I recommend this journal very much to colleagues.

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S Munshi

Dr.Tania Muñoz, My experience as researcher and author of a review article in The Journal Clinical Cardiology and Interventions has been very enriching and stimulating. The editorial team is excellent, performs its work with absolute responsibility and delivery. They are proactive, dynamic and receptive to all proposals. Supporting at all times the vast universe of authors who choose them as an option for publication. The team of review specialists, members of the editorial board, are brilliant professionals, with remarkable performance in medical research and scientific methodology. Together they form a frontline team that consolidates the JCCI as a magnificent option for the publication and review of high-level medical articles and broad collective interest. I am honored to be able to share my review article and open to receive all your comments.

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Tania Munoz

“The peer review process of JPMHC is quick and effective. Authors are benefited by good and professional reviewers with huge experience in the field of psychology and mental health. The support from the editorial office is very professional. People to contact to are friendly and happy to help and assist any query authors might have. Quality of the Journal is scientific and publishes ground-breaking research on mental health that is useful for other professionals in the field”.

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George Varvatsoulias

Dear editorial department: On behalf of our team, I hereby certify the reliability and superiority of the International Journal of Clinical Case Reports and Reviews in the peer review process, editorial support, and journal quality. Firstly, the peer review process of the International Journal of Clinical Case Reports and Reviews is rigorous, fair, transparent, fast, and of high quality. The editorial department invites experts from relevant fields as anonymous reviewers to review all submitted manuscripts. These experts have rich academic backgrounds and experience, and can accurately evaluate the academic quality, originality, and suitability of manuscripts. The editorial department is committed to ensuring the rigor of the peer review process, while also making every effort to ensure a fast review cycle to meet the needs of authors and the academic community. Secondly, the editorial team of the International Journal of Clinical Case Reports and Reviews is composed of a group of senior scholars and professionals with rich experience and professional knowledge in related fields. The editorial department is committed to assisting authors in improving their manuscripts, ensuring their academic accuracy, clarity, and completeness. Editors actively collaborate with authors, providing useful suggestions and feedback to promote the improvement and development of the manuscript. We believe that the support of the editorial department is one of the key factors in ensuring the quality of the journal. Finally, the International Journal of Clinical Case Reports and Reviews is renowned for its high- quality articles and strict academic standards. The editorial department is committed to publishing innovative and academically valuable research results to promote the development and progress of related fields. The International Journal of Clinical Case Reports and Reviews is reasonably priced and ensures excellent service and quality ratio, allowing authors to obtain high-level academic publishing opportunities in an affordable manner. I hereby solemnly declare that the International Journal of Clinical Case Reports and Reviews has a high level of credibility and superiority in terms of peer review process, editorial support, reasonable fees, and journal quality. Sincerely, Rui Tao.

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Rui Tao

Clinical Cardiology and Cardiovascular Interventions I testity the covering of the peer review process, support from the editorial office, and quality of the journal.

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Khurram Arshad